The present invention relates to travelling-wave looms and, more particularly, it relates to methods of and apparatus for supplying weft thread carriers (shuttles) used thereon.
At present, there are known methods of supplying weft thread carriers wherein a weft thread is fed in one direction from a bobbin for winding in the form of coils by a thread guide onto a spool of a carrier, with a free end of the weft thread gripped preliminarily. In a space between the thread guide and the bobbin the thread is braked. Subsequently, after the winding is completed, each carrier is admitted into a weaving zone, with an elongated section of the weft thread formed between this carrier and the thread guide, after which the coils of the weft thread are separated from the elongated section at the edge of the looming-up zone and a portion of the elongated section is sequentially pulled through a grip and the thread guide in a direction opposite to that of the feed for the elongated section to be compensated for, the pulling of the portion of the elongated section in the opposite direction being achieved by pulling in a direction normal to the direction of advance of the thread and by forming a loop intermediate of the braking point and the thread guide.
A known apparatus for practicing this known method comprises grips for the end of the weft thread arranged on a rotatable horizontal disk as well as thread guides installed on the disk so as to be rotatable around their own axes which extend parallel to the axis of rotation of the disk. The thread guides wind the thread nipped by the grip and unwound from a bobbin, in the form of coils onto the spools of carriers admitted successively by a conveyer into a weaving zone thereby forming a straight elongated section of the thread. Additionally, the apparatus includes a device for braking the thread unwound from the bobbin, a device for separating the elongated section from the coils and a device for compensating for a portion of the straight section by pulling that portion through one of the grips and the thread guide in a direction opposite to that of feed. The disk of the apparatus carries bell cranks entrailed by the thread for said loop to be formed which execute oscillatory motion in the horizontal plane.
Due to availability of the thread loop the thread is subjected to an additional mechanical action of the bell crank which, in turn, causes fraying and eventual breaking of the thread.
Besides, the location of the bell crank on the disk encumbers the zone thereby rendering the servicing of the apparatus inconvenient. If the weft thread breaks, the time required to repair the break is increased due to the fact that the weaving zone is encumbered and also due to the elimination of the break.